is halfway between a "what if" and a "paper panzer", between the two wars there have been at least couple of similar projects, the Germans have built a prototype of "Ball Tank" which is at the Kubinka museum, and a Texan designer had a project very similar to that of the model but he never left the drawing board

The ball is rolling along "at speed"... suddenly, the ball falls into a dip - maybe a shell-hole full of sticky mud, maybe a trench, maybe just a natural dip or tiny stream-bed - encountering obstacles in the terrain happens "all the time" to tanks crossing battle-fields… And, just like that, the ball's track stops rolling...

Now it's the crew's turn to be like hamsters in a suddenly-stopped hamster-ball and take a powered spin around inside their metal beach-ball!

Ball and ring-tanks... It's a crazy idea!

But I'm going to get this MiniArt kit! Crazy it is, but neat as all H**L! I think perhaps I'll go for a "field-mod" and create some tricycle training-wheels for it (make it easier to display on a table, too! )

In most cases all the ball tank have a stationary cage inside and the outside slides around it, so the hamster example won't happen in a normal driving situation.

The miniart kit already has "training wheels", the AMG BT-102 kit does not. The AMG kit use chalk blocks to help with the display. I like most things about the miniart kit over the AMG kit but the 37mm(?) cannons seem over the top and the "training wheels" don't seem stronger enough to not knock it over when fired. Even if it could stand up, the crew comfort/safety doesn't suggest a crew will be working well for long. The AMG kit has a prop and suggests it could be submerged more then 1/2 way. That would be another good way to kill the crew if it was employed.

In most cases all the ball tank have a stationary cage inside and the outside slides around it, so the hamster example won't happen in a normal driving situation.

The miniart kit already has "training wheels", the AMG BT-102 kit does not. The AMG kit use chalk blocks to help with the display. I like most things about the miniart kit over the AMG kit but the 37mm(?) cannons seem over the top and the "training wheels" don't seem stronger enough to not knock it over when fired. Even if it could stand up, the crew comfort/safety doesn't suggest a crew will be working well for long. The AMG kit has a prop and suggests it could be submerged more then 1/2 way. That would be another good way to kill the crew if it was employed.

So... What happens to you when your car suddenly stops? Last I heard, the laws of physics still pertain! The wheels stopped rolling does not mean that the attached car and its contents stopped equally fast. Momentum rules. A good illustration is when the chain attaching the rear-end of a car to a solid post brings that axle to a sudden stop when the driver tries to zoom away - and the rest of the car continues on down the road. (Yes, that really does work!)

The ball-in-a-ring isn't different. The ball applies thrust to the track to roll it by "climbing up the hill". The ball is "running" inside the ring when the tank is rolling. The ball can remain at some level orientation (your "stationary frame"...)just as long as its ring continues to move down and under the ball commensurate to the force the ball exerts on that ring. Stop the ring, and unless that ball IMMEDIATELY stopped exerting force AND simultaneously looses all its momentum, it will continue to "climb the hill"... Even if the ball immediately shifted to "neutral" and applied no more thrust to the ring, its momentum would continue it up its hill. AKA, the "hamster ball effect".

Try spinning a raw egg and suddenly stop it - and then let it go. It will resume spinning for this very scenario (because the egg mass is still trying to spin and is actually attached to its shell!). Or place a glass of ice and water centrally on a "lazy Susan", spin it up, and then stop the "susan"... The water and ice continue to spin. But the glass and the "susan" will not - because the water and ice are not very well attached to their container glass (relative to the mass of the "susan, etc."). Now, IF the glass had a set of vanes in it - functionally improving the attachment of the water-mass to its container - you would see a version of the "sudden stop catastrophe" when you stop the spinning "susan". The GLASS would continue to try to spin along with its contents...

The ball and frame inside its track-ring is not expected to be totally "free" to continue moving regardless of what that ring does - but it WILL continue trying to move... and because it is inside a ring, that continued movement will translate into "climbing up the hill in front of it". The funnest outcome would be for the ball to be "in neutral", and disengaged from the ring and simply continue climbing and be a hamster in a stopped ball, and eventually exhaust its momentum and then come back down and climb up the back hill, in a series of ever-decreasing swings of the "pendulum".... All other outcomes are likely to be messier and much harder on the crew!

Now available for pre-order at Hobby Easy for a little more than $35. Release date of 10/3/18. Gotta get one of these for a "Pac-man" attack diorama thru some low ruined walls. Those old enough to remember what Pac-man was will know what I mean. Maybe have german Zundapps with colored sidecars chasing it.

In most c.... The funniest outcome would be for the ball to be "in neutral", and disengaged from the ring and simply continue climbing and be a hamster in a stopped ball, and eventually exhaust its momentum and then come back down and climb up the back hill, in a series of ever-decreasing swings of the "pendulum".... All other outcomes are likely to be messier and much harder on the crew!

SOMETHING will have to "give"!

Cheers! Bob

I think I prefer trying to walk away from a sudden stop with my head spinning (and probably my latest meal all over me) than having my head smacked against the inside of a normal vehicle. There was also some inventor trying a mono wheel motorcycle based on the same principle.Trying to do wheelies would look really silly ....https://www.youtube.com/watch?v=sVex_mDcMgk/ Robin